Customer side power management system including auxiliary fuel cell for reducing potential peak load upon utilities and providing electric power for auxiliary equipment

ABSTRACT

A customer side power management system including at least one auxiliary fuel cell(s) source is provided. When the power derived from the electric utility reaches a predetermined threshold level, all remaining power needed to supply the customer&#39;s loads is obtained from the at least one hydrocarbon powered fuel cell which is/are located within the customer&#39;s facility. In such a manner, high peak demand utility charges are avoided by the customer, and the simple cost effective power generation from the fuel cell is provided.

This is a continuation of application Ser. No. 09/251,217, filed Feb.16, 1999, now U.S. Pat. No. 6,084,318, which is a continuation ofapplication Ser. No. 08/856,187, filed May 14, 1997, now U.S. Pat. No.5,880,536, the entire contents of which are hereby incorporated byreference in this application.

This invention relates to a customer side power management systemincluding an auxiliary fuel cell disposed at a customer location forreducing peak demand potential upon a corresponding electric utility.More particularly, this invention relates to a system and method forreducing the customer's peak power demand charges from the electricutility by way of the provision of an on-site auxiliary fuel cell whichkicks into effect (e.g. outputs additional power) upon the customerreaching a predetermined demand electric power level.

BACKGROUND OF THE INVENTION

Customers or users of large amounts of electric power typically consumesuch power at uneven or sporadic rates. This is especially true forcustomers with highly punctuated loads, that is, having many pieces ofequipment with frequent stops and starts. Such customers can be expectedto build random and cumulative peaks in their power demands.

A typical daily load profile for many industrial manufacturingfacilities, retail establishments, and the like, is made up of severalrandomly acting loads, such as shown in prior art FIGS. 1A-1D. FIG. 1Aillustrates a constant twenty-four hour lighting load. FIG. 1Billustrates semi-random punctuated load. FIG. 1C illustrates semi-randomlonger cycle loads. FIG. 1D illustrates a composite idealized daily loadprofile, showing high stochastic peaks arising randomly throughout theday.

Despite these fluctuating demands for electric power, electric utilities(e.g. PEPCO) are required to maintain a generating capacity that exceedsthe maximum demand for electricity anticipated during any given periodof time. Therefore, electric utilities must maintain generatingcapacities far in excess of average electric power requirements in orderto meet such occasional and relatively short term demands. The formationand maintenance of such excess capacities is quite expensive,dramatically increases the average cost of providing electric power tocustomers, and create excessive pollution in the environment.

In order to better allocate the cost of providing excess powergeneration capacity to those customers most requiring such capacity, andin order to encourage such customers to distribute their demand forelectric power, the utility rates schedule to such customers istypically divided into at least two components. The first component isan energy usage charge which reflects the utility's own energygeneration and transmission costs. This charge is typically calculatedin cents per kilowatt (KW) hour of energy consumed during a particularbilling period. The second component of the bill is a peak demand chargewhich reflects the utility's capital costs, and is based on thedeviation from average energy consumed by the customer during apredetermined demand interval period of time. The peak demand charge iscalculated as cents, or dollars, per kilowatt of actual peak demand.Such peak demand charges can be quite high as a percentage of the totalutility charge over a predetermined billing period.

Owing to the increased use of greater peak demand charges by electricutilities, large consumers of electricity have begun investigatingmethods for reducing peak power demands from the utility. One approachis sequencing equipment use so that only an acceptable predeterminednumber of load contributors are allowed to operate simultaneously.Unfortunately, this method is expensive to control and restrictive tocustomers.

U.S. Pat. No. 5,369,353 discloses an apparatus that stores energy duringperiods when excess supply is available, and then releases that energyduring times of higher demand. Unfortunately, the apparatus of the '353patent utilizes a battery, for example, for the energy storage device.The use of a battery for this application is expensive and burdensome,and requires the addressing of recharging issues, replacing suchbatteries, the expensive nature of the batteries themselves, etc.

U.S. Pat. No. 5,500,561 discloses a power management system includingprimary and secondary sources of electricity. The system senses peakpower demands for electricity and switches a particular load of thecustomer to a secondary source (e.g. storage battery) so as to reducepeak power demands. Unfortunately, a secondary source disclosed in the'561 patent is also a battery. Thus, the system of the '561 patentsuffers from problems similar to those discussed above relating to the'353 patent. Batteries as providers of secondary electricity areundesirable.

It is apparent from the above that there exists a need in the art for apower management system, including a secondary or auxiliary source, thatis more cost effective and simpler to utilize than those discussedabove.

This invention will now be described with respect to certain embodimentsthereof, accompanied by certain illustrations, wherein:

SUMMARY OF THE INVENTION

This invention generally fulfills the above-described needs in the artby providing a customer side electrical power management systemcomprising:

a main distribution channel, located at a customer location, forreceiving electric power from a public electric utility via a pluralityof phase lines or wires, said distribution panel for thereafterdistributing the received electric power toward a plurality of loads atthe customer location;

At least one hydrocarbon-powered fuel cell located at the customerlocation that receives hydrocarbon fuel and transforms same intoelectric power to be directed to said loads;

a threshold level setting circuit located at the customer location forallowing the customer to set a maximum power level of power from saidutility that the customer wishes to receive and paid for, in order toreduce peak demand charges;

a comparator for determining when the amount of power being received bythe customer from said utility reaches said maximum power level; and

means for causing all additional power required by the customer that isabove said maximum power level to be generated by said at least one fuelcell and to be directed from said at least one fuel cell to said loadsthereby reducing the peak demand charges to the customer.

IN THE DRAWINGS

FIGS. 1A-1D are prior art graphs of demand for electric power versustime for typical customer loads.

FIG. 2 is a block diagram of a customer side, power management systemformed in accordance with certain embodiments of this invention.

FIG. 3 is a block diagram of the hydrocarbon powered fuel cell to beused in conjunction with the embodiment of FIG. 2, according to certainembodiments of this invention.

FIG. 4 is a graph of demand for electric power against time, due to theimplementation of certain embodiments of this invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like parts throughout the severalviews.

Referring now to FIGS. 2-5, it will be seen that a customer side powermanagement system formed in accordance with the present invention may beeasily interconnected with existing electric power wiring of a typicalcustomer's facility in order to monitor load requirements of a customer.To facilitate an understanding of the invention, FIG. 2 shows threephase power wiring (i.e. wires labeled L1, L2, and L3 representing thedifferent phases) and a neutral (i.e. end) wire coming from the utility1 and being received by the customer facility 4. The three phase wiresL1, L2, and L3, along with neutral wire N, are received by a maindistribution panel 2 located at the customer facility. Main distributionpanel 2 distributes the electric power throughout customer facility 4,and in many cases provides power to, for example, lighting distributionpanel 6 which distributes power to the various lighting circuits of thecustomer's facility. Thus, main distribution panel 2 conventionallydistributes the three phase power wiring generated by the electricutility throughout the customer facility and in doing so distributespower to the various loads served by the customer facility.

As illustrated in FIGS. 1A-1C, there are three types of common ACelectrical loads which may be required to be satisfied by the ACelectrical power generated at the public utility 4 and emanating towardand from the illustrated consumer facility. These three loads are thelighting load (FIG. 1A), semi-random punctuated loads (FIG. 1B), andsemi-random longer cycle loads (FIG. 1C). Thus, the three phase powerwirings L1, L2, and L3 along with neutral wiring N connect from thepublic utility side of the main distribution channel 2 and issuetherefrom as AC electrical conductors 7 on the customer side of panel 2and thereafter into connection or communication with the composite ofloads which are required to be satisfied by the power emanating fromutility 1.

In accordance with the instant invention, in addition to the AC powerdistributed by panel 2, there is provided hydrocarbon powered fuel cell10 along with power distribution circuit 12, each also at the customerfacility. Essentially, original or additional power from fuel cell 10 isgenerated and supplied to the customer's loads when it is determined bymeans within circuit 12 that the level of power being derived from theutility 1 has reached a predetermined power threshold or level as willbe discussed further below. At this time, the fuel cell 10 will eithergenerate additional electric power or start to generate such power, sothat no more power is required from the public utility 1.

Referring now to FIGS. 2 and 5, power distribution circuit 12 will bedescribed in further detail. Firstly, circuit 12 receives an input(s)from either distribution panel 2 or directly from the lead lines L1-L3from the utility, this input being designated by reference numeral 14,and is indicative of the power being derived by the customer's loadsfrom the electric utility. Comparator 16 functions to compare the poweror level of signal 14 with a predetermined threshold level set bycircuit 18 so as to determine whether the power level being derived fromthe utility by the customer's loads has reached the predeterminedthreshold level which necessitates kicking in the power (original oradditional) from the fuel cell 10. When comparator 16 determines thatthe power being derived from the utility has not yet reached thepredetermined threshold level, switch 18 remains closed and the utility(i.e. lines L1-L3) remains the sole supply of power for the customer'sloads. Optionally, even before the threshold level is met, the fuel cellmay be used to generate some amount of power in order to maintainefficiency or save power costs.

However, when comparator 16 determines that signal 14 has reached thepredetermined level set by user-controlled circuit 18, comparatorinstructs switch 20 to open thereby allowing original or additionalelectric power from fuel cell 10 to aid in supplying power to thecustomer's loads. Optionally, a predetermined amount of power 22 fromthe fuel cell may always be supplied to the loads regardless of whetherswitch 20 is opened or closed. In other embodiments, when the level isreached, circuit 12 directly instructs the fuel cell 10 via line 13 togenerate original or additional electric power. Thus, circuit 12controls the distribution of power from and between the utility and thefuel cell, whereby additional electric power from cell 10 is directedtoward the customer's loads so as to supply same whenever thepredetermined threshold level set by circuit 18 has been reached by thepower being derived from the utility.

FIG. 3 is a block diagram of fuel cell 10 according to certainembodiments of this invention. As illustrated, fuel cell 10 is poweredby natural gas or other known hydrocarbon materials from source 26. Thisfuel makes it way to fuel processor 28 which interacts with fuel cellstack 30 and power conditioner 32 in a known manner so as to generate ACpower 21 and/or 22 which is directed toward the customer's loads to bepowered.

FIG. 4 illustrates an exemplary demand versus time of day graphresulting from certain embodiments of the instant invention. Due to theutilization of the power from the fuel cell whenever the predeterminedutility power level being received has reached a predetermined level,the utility load profile paid for by the customer may remainsubstantially flat and thereby allowing the customer to avoid payment ofcostly peak demand charges as described in the background herein.

Once given the above disclosure, many other features, modifications, andimprovements will become apparent to the skilled artisan. Such otherfeatures, modifications, and improvements are therefore considered to bea part of this invention, the scope of which is to be determined by thefollowing claims:

I claim:
 1. A method of operating a customer side electrical powermanagement system, the method comprising the steps of: receivingelectric power from a public electric utility via at least one phaseline or wire, and thereafter distributing the received electric powertoward at least one load at a customer location; providing at least onehydrocarbon-powered fuel cell at the customer location, the at least onehydrocarbon-powered fuel cell receiving hydrocarbon fuel andtransforming the hydrocarbon fuel into electric power to be directed tothe load; providing a threshold level setting circuit at the customerlocation, the threshold level setting circuit allowing a customer to seta maximum power level of power from the utility that the customer wishesto receive and pay for; determining when the amount of power beingreceived by the customer from the utility reaches the maximum powerlevel; and causing all additional power required by the customer that isabove the level to be generated by the at least one fuel cell to bedirected from the at least one fuel cell to the load.